By forcing blogs to converge into one of the bigger clusters, censorship encourages the formation of densely-knitted, almost impenetrable ana-mia cliques. This favours bonding, but also information redundancy – meaning that pro-ana-mia bloggers will tend to exchange messages, links and images among themselves and to exclude other information sources. Imagine you are a medical institution trying to put in place an information and awareness campaign on the risks of extreme fasting or exercise. Because of the toothpaste tube effect, it is clearly more difficult to reach out to ana-mia bloggers now than two years ago. If in 2010 a public health information campaign would target the Web sites in the middle of the graph and hope they relay the message to the margins, in 2012 the middle is virtually deserted. The only option is to cut through the dense clusters and hope your message will reach one of the more central influencers. But this is clearly a long shot. Ana-mia Internet users are constantly putting in place new strategies to elude general public visibility. Websites use cryptic language, password protections, and special software applets to circumvent search engine indexing. For these sites, censorship is a risk they have to constantly manage by fine-tuning their visibility.
Some breathtaking analysis here by Antonio A. Casilli.